Preparation of norbornenes

ABSTRACT

NORBORNENE AND ALKYL SUBSTITUTED NORBORNENES ARE MADE BY CONTINUOUSLY CONDENSING OLEFINS SUCH AS ETHYLENE, PROPYLENE, ETC. WITH DICYCLOPENTADIENE OR CYCLOPENTADIENE IN THE PRESENCE OF AN INERT SOLVENT IN A PRESSURIZED REACTOR. INCREASED YIELDS OF THE DESIRED NORBORNENES ARE OBTAINED BY RECYCLING THE BY-PRODUCTS BACK TO THE REACTOR TO REACT WITH ADDITIONAL OLEFINS.

United States Patent 2 3,766,283 PREPARATION OF NORBORNENES Nicholas B. Lorette, Lake Jackson, Tex., assignor to The Dow Chemical Company, Midland, Mich. No Drawing. Filed Mar. 27, 1972, Ser. No. 238,465

Int. Cl. C07c 3/04 US. Cl. 260 -666 PY 8 Claims ABSTRACT OF THE DISCLOSURE Norbornene and alkyl substituted norbornenes are made by continuously condensing olefins such as ethylene, propylene, etc. with dicyclopentadiene or cyclopentadiene in the presence of an inert solvent in a pressurized reactor. Increased yields of the desired norbornenes are obtained by recycling the by-products back to the reactor to react with additional olefins.

BACKGROUND OF THE INVENTION This invention relates to a process for the preparation of norbornene and alkyl substituted norbornenes by the reaction of lower olefins and cyclopentadiene or dicyclopentadiene in an inert hydrocarbon solvent.

It is known from the US. Pat. 3,007,977 to A. B. Hill et al. that norbornylene can be obtained by the reaction of ethylene with impure cyclopentadiene dimers at selected high temperatures and pressures.

However, this process is disadvantageous in that considerable amounts of carbon and resinous material are formed with a slow buildup in the reactor and the associated equipment.

SUMMARY OF THE INVENTION It now has been discovered that the preparation of norbornenes can be accomplished by reacting lower olefins with cyclopentadiene in the presence of an inert solvent with high selectivity to norbornenes and with reduced carbon or resin formation.

The process of this invention comprises generally the steps of continuously feeding a lower olefin and a solution of dicyclopentadiene in an inert solvent into a reactor with a substantial excess of olefin, maintaining the temperature, pressure, and residence time in the reactor such that formation of norbornenes are favored and recovering norbornenes from the reaction by-products by distillation.

The more limited process steps comprise feeding a lower olefin and a solution of dicyclopentadiene in an inert solvent into a reactor at a mole ratio in the range from about 1:05 to about 10:1 of olefin to dicyclopentadiene, maintaining the reactor at a temperature in the range of from 200 to 325 C., a pressure in the range from 100 to 2000 p.s.i.g. with a residence time of from one-fifth to hours of the reactants in the reactor and recovering norbornenes from the reaction products by distillation.

It has also been found that the reaction by-products from the distillation with additional solvent can be recycled to the .reactor with additional lower olefin to generate additional norbornenes. The norbornenes produced are useful in that they can be converted into toluene or alkyl benzenes.

DETAILED DESCRIPTION The process of this invention is achieved by condensing normal lower alpha mono-olefins such as ethylene, propylene, butene-l, pentene-1, hexene-l, with dicyclopentadiene under selected temperatures and pressures to produce norbornene or alkyl substituted norbornenes.

The alpha olefins used in this process are of a commercial grade having a purity greater than about 50% with less than about 15% by weight of a diolefin content,

ice

or 50% of alkane content. It is preferred to use a higher purity olefin.

The cyclopentadiene plus dicyclopentadiene used in this invention is readily available as a by-product from the steam cracking of hydrocarbons. A crude C cut from the steam cracking of naphtha and hydrocarbon gases containing 2025% by weight of cyclopentadiene (CPD) plus dicyclopentadiene (DCPD) with the remainder isoprene, piperylene and other C hydrocarbons is the normal starting material. Greater or less CPD plus content may be used.

In this invention, dicyclopentadiene was used as a source of cyclopentadiene. It is well known that at tem peratures above 180 C., dicyclopentadiene rapidly decomposes to two moles of cyclopentadiene. Cyclopentadiene would work as a feed equally as well as does dicyclopentadiene.

The solvents used in this process are high boiling inert solvents having a boiling point greater than about C. Examples of these are commercial aromatic hydrocarbons such as xylene, diisopropyl benzenes, toluene,

ethyl methyl benzenes, trimethyl benzenes, naphtha, and the like.

If desired other high boiling compounds can be used such as ethylene glycol, alkyl ethers, phenyl ethers, and the like. However, the use of hydrocarbon solvents is preferred.

The temperature of the reaction can vary from about 200 to about 325 C. with the preferred range being from about 220 to about 290 C.

The pressure of the reaction can vary from about 100 to about 2000 pounds per square inch gauge with the preferred range being from about 200 to about 1000 p.s.1.g.

The residence time of the reactants in the reactor varies from about one-fifth to 5 hours with the preferred time being from about /s to 2 hours.

The above lower olefins and dicyclopentadiene in an inert solvent are fed into a reactor such that the mole ratio of olefin to dicyclopentadiene is in the range from about 1.0205 to about 4.0:1.0.

The reactor used in this process is not critical provided that the reactor walls are inert to the reaction. Stainless steel is the preferred material.

The following examples are presented solely to illustrate and not limit the invention.

Example 1 A 15.5 weight percent solution of dicyclopentadiene (DCPD, the dimer of cyclopentadiene) in a commercial xylene cut (containing in percent by weight about 17% ortho, 52% meta, and 9.0% para xylene isomers together with about 22.0% ethyl benzene) was pumped into the bottom of a stainless steel reactor 39 inches long having from a pressure cylinder at a rate such that the mol ratio of ethylene to cyclopentadiene was 2.3.

The pressure in the reactor was regulated to 800 pounds per square inch gauge (p.s.i.g.) by adjustments in a regulator downstream from the reactor.

All liquid and gas reactants passed upwardly through the reactor and through the regulator to have the pressure reduced to atmospheric. Substantially all the products except ethylene were condensed in an ice and Dry Ice train I and recovered.

The liquid products were then distilled in a 15 plate I distillationcolumn to recover norbornene. The results of this example and similar examples using the same procedure are set forth in Table I.

The combined bottoms from the distillation of Examples 23 and 24 were then diluted with additional commercial xylene to obtain a solution of about 15% by weight of distillation bottoms in the xylene, i.e. the feed material in Table II hereinafter. This solution was then fed back to the same reactor operating at 800 p.s.i.g. with excess ethylene being concurrently fed into the bottom thereof. The temperature of the reactor and the residence time was varied as set forth in the four experiments of Table II. The condensed products were distilled as before and analyzed by a gas chromatograph to give the analyses in Table II.

Table II thus shows that an additional yield of norbornene can be obtained b returning the distillation bottoms to the reactor.

Similar results are obtained when using a continuous recycle of the bottoms to the reactor with a blending thereof with fresh feed of DCPD.

In a manner similar to the .preceding'examples, a feed of 27.5% DCPD in the commercial xylene of'Examples 126 was pumped into the bottom of a 12 inch by one inch 0.D., (outside diameter) stainless steel reactorcontaining no packing, maintained at the temperature and pressure given below.

Propylene was fed into the bottom of the reactor in TABLE IIL-P REPA RATION 0F fi METHYL-2-NO BBO RNENE methyl-norbornene; MHHDMN =-7 methyl-heptahydro[1,4,5,8]

dimcthanonaphthalcnc.

TABLE I.PREPARATION OF NORBORNggIIiIEROM E'IHYLEN'E AND DICYCLOPENTA V Mole percent Reac- Wt. percent Feed tion Conver: Percent selectivity' DCPD in ratio time, sion feed C /CPD T., C P.s.1.g hour 7 CPD NB OHDMN 15. 5 2. 3 200 800 1. 9 82. 1 87. 5 8. 7 15. 5 2. 3 220 899 1. 9 95; 9 a 85. 5 9. 3 15. 5 2. 3 220 800 1. 9 89. 8 86. 9 19. 8 15. 8 5. 0 200 600 1. 9 73. 9 82. 1 8. 5 15. 8 5. 0 220 600 1. 9 93. 2 81. 2 11. 6 15. 8 5. 0 240 699 1. 9 97. 8 84. 0 11. 9 15. 8 2. 0 200 600 1. 9 76. 6 82. 2 6. 5 15. 8 2. 0 220 600 1. 9 94. 9 82. 6 V 12. 4 15. 8 2. 0 240 600 1. 9 97. 5 80. 7 14. 1 15. 8 5. 0 299 400 1. 9 60. 7 74. 3 10. 9 15. 8 5. 0 220 490 1. 9 85. 5 75. 4 14. 3 15. 8 5. 0 249 490 1. 9 93. 1 77. 5 14. 3 15. 8 2. 0 200 400 1. 9 63. 0 77. 2 11. 8 15. 8 2. 0 220 400 1. 9 88. 2 70. 9 17. 2 15. 8 2. 9 249 499 1. 9 96. 2 70. 8 16. 8 15. 8 0. 9 220 400 1. 9 I 88. 8 65. 4 20. 2 28. 3 2. 0 220 400 1. 9 84. 6 63. 3 22. 2 28. 3 2. 0 220 600 1. 9' 91. 2 70. 0 19. 9 28. 3 2. 0 229 809 1. 9 94. 4 79. 6 14. 9 42. 4 2. 0 220 490 l. 9 81. 9 57. 1 23. 9 42. 4 2. 0 220 600 1. 9 89. 9 66. 2 23. 5 42. 4 2. 0 220 809 1. 9 93. 4 71. 7 20. 7 15. 1 2. 2 260 800 0. 9 98. 7 86. 3 9. 8 15. 1 1. 7 260 800 0. 6 97. 1 83. 5 11. 9 8. 0 1. 8 270 899 0. 4 96. 4 87. 5 8. 5 8. 0 1. 7 285 809 0. 4 97. 4 89. 8 7. 1

Norm-DCPD=dicyclopentadiene; CPD=cyclopentadiene; NB =norbornene; OHDMN=octahydro- 5, SI-dimethanonaphthalene; C =ethylene.

TABLE IL -REACTION OF ETHYLENE WITH OHDMN AND OTHER HEAVY BY-PRODUOTS FR PRODUCE NORBORNENE OM THE REACTION OF ETHYLENE WITH CPD TO Weight percent in product NOTn.-OHDMN:octahydro-[1,4,5,S]-dimethanonaphthalene; CPD=cyclopentadiene; DCPDzdicyclopentadiene; Heavieszheavy by-prpducts from the reaction of ethylene plus CPD; tentative identification as tricyclopentadlene and trieyclopentadiene plus ethylene," and several unknowns; NAzno analysis.

5 6 TABLE NPREACTION F PROPYLENE WITH 7 METHYL 2-6 carbons and a solution of dicyclopentadieneor HEPTAHYDRO-[l,4,5,8]-DIMETHANONAPHTHALENE TO cyclopentadiene in an inert solvent having a boiling PRODUCE ADDITIONAL E'METHYL'NO RBORNENE point greater than about 100 C. into a reactor with Wei ht ercent a substantial excess of olefin,

(2) maintaining the temperature, pressure, and resi- MNB MHHDMN CPD DCPD Heavies dence time in the reactor such that formation of nor- ??83555":::::::::::: 5233 iii? in; tit til bornenes are favored,

(3) recovering norbornene or S-alkyl norbornenes from NorE.-MNB=5methyl-norbornene;MHHDMN=7-methyl-heptahythe reaction by products by distillation and dro-[l,4,5,8]-dimethanonaphthalene; Heavies=trieyclopentadiene the Diels-Alder reaction product of CPD and MHHDMN, and similar (4) feeding said by-products in sand lnert solvent with higher Mung Mensamn products additional amounts of said lower olefin back to said reactor to generate additional norbornene or S-alkyl norbornenes. 2. A process for the preparation of norbornene or 5- alkyl norbornenes in which the steps comprise (1) feeding a normal lower alpha mono olefin having 26 carbons and a solution of dicyclopentadiene in E l 28 an inert solvent having a boiling point greater than about 100 C. into a reactor at a mole ratio in the Following the same procedure and using the same equiprange from about 1:0.5 to about 10:1 of olefin to ment as in Example 7, butene-l was used in place of 2 Y lOpcrltadienle, h propylene and diisopropyl benzene was usedasthe solvent. mamtammg t e reacsor at a tempertmre m t e h l f th b1 range of from 200-325 C., a pressure in the range The conditions used andt e resu ts are set or m Ta es of from 1O0 20O0 with a residence time of V and VI. from /5 to 5 hours of the reactants in the reactor,

TABLE V.PREPARATION OF 5-ETHYL-2-NORBORNENE Molar Mole percent feed Percent ratio Reaction Percent selectivity DCPD in butenetime Converfeed 1/CPD T.,C. P.s.i.g. (hours) sion CPD ENB EHHDMN Norm-ENE =5-ethyl-2-norbornene; EHHDMN =7-ethy1-heptahydro [l,4,5,8]-dimethanonaphthalene. TABLE VI.REACTION 0F BUTENE-l WITH 7-ETHYL-HEP recovering norbornene y norbornenes from TAHYD R04 .4. T0 0 the reaction by-products by distillation and DUCE ADDITIONAL RBORNENE (4) feeding said reaction by-products in said inert sol- Weight percent vent with additional amounts of said lower olefin ENB EHHDMN CPD DCPD Heavies 40 lacl: to saigl ileaftor Ito generate additional norornene or -a y nor ornenes. 1 .4 533, 65: 8; 3 0.25 332 2 3. The process of claim 2 1n wh1ch the lower olefin 1s 1 88 wt ercent x lene solvent ethylene fi r i1ene; EHH ethypheptahydm. 4. The process of claim 2 in which the lower olefin 1S [I,4,5,8 idiimethazionaphtihalene;CPflgEAggggknfiglopertadienei Zhe r 1 'ar er l i iil 1gc0I?d:1 S%iii% l 1 1 i%d i 1%t:. an Sum Hg 5. The process of claim 2 m which the lower olefin 1s Example 29 butene'l 6. The process of claim 2 wherein the solvent is an aro- A C-5 distillation cut obtained from the steam pyrolysis matic hydrocarbon l of liqllified Petroleum gas was used as SOIJI'CB 0f y 7. In a process for the preparation of norbornene or Pentadiene and dicyclopentadielle- The cut Was S-alkyl norbornenes by feeding a normal lower alpha diluted with xylene and the mixture was allowed to react mon lefin having 2 6 carbons d dicyclopentadiene with ethylene in a manner similar to Example 1. The into a reactor with a substantial excess of olefin, maintainreactlon temperature Was Pressure 600 P- -g-, ing the temperature, pressure and residence time in the and reaction time 4 hours. The results are listed in Table VII. Note that there was an 88% yield of norbornene reactor such that formation of norbornenes are favored,

based on the converted cyclopentadiene and dicyclopenthe reaction by-products by distillation, the improvement tadiene. which consists of carrying out the reaction in the presence TABLE VH REACTION OF ETHYLENE WITH CYCLO of from 50 to 90% by weight based on the dicylopentadi- PENTADIENE IN A MIXTURE OF 0-6 HYDROCA S ene of an inert solvent having a boiling point greater than Grams about 100 c.

8. The process of claim 7 wherein the solvent is an Feed Pmduct aromatic hydrocarbon solvent.

i ii -im 13.0 11.2

i3aaa1..- :31: it; 13:3 References CM 8231935522 53? :3: 3:3 3:? UNITED STATES PATENTS ittiifiifiifiifiae: 33:: 12:? 315 ii aiir iv i'i Norbornene 0. 0 25.

1 All conjugated dienes in the 0-5 out are listed. The stream contained in minor quantities many other 0-5 compounds not listed. DELBERT GANTZ Primary Exammer What I claim is: V. OKEEFE, Assistant Examiner 1. A process for the preparation of norbornene or 5- alkyl norbornenes in which the steps comprise US, Cl, X R,

(1) feeding a normal lower alpha mono olefin hav'mg 260666 A 

